1. Field of the Invention
The present invention relates to a structure of installing a wire harness for a sliding door, and more particularly to the structure of installation in which the wire harness is installed from a sliding door side toward a vehicle body side employing a harness protective tube such as a corrugated tube in an oval shape so that slack of the wire harness following opening and closing movement of the sliding door can be absorbed.
2. Description of the Related Art
There have been proposed various kinds of structures of installing wire harnesses for sliding doors in order to supply electric power from a vehicle body (power supply) to functional components in the sliding doors which are employed in a one boxed car or a station wagon, or to send electric signals from the sliding door to the vehicle body.
The sliding door is equipped with various functional components such as a power window motor, door lock unit, speaker, switch unit, electronic control unit, etc. to or from which electric power or signal currents are supplied or received. It is necessary to supply or receive the electric power not only while the door is closed but while the sliding door is open.
FIGS. 6A and 6B show an example of a conventional structure of installing a wire harness for a sliding door which is disclosed in Japanese Patent Laid-open Publication No. 7-222274.
In this structure, a reel 120 capable of feeding and taking up an electric wire (wire harness) 119 according to opening and closing movement of a sliding door 118 is provided on a vehicle body 121. One end of the wire 119 is connected to a speaker 123 which is a door side functional component by means of hinge 122, and the other end of the wire 119 is connected to an audio apparatus (not shown) which is a vehicle body side functional component.
When the sliding door 118 is closed as shown in FIG. 6A, the wire 119 is fed from the reel 120 and extends, and when the sliding door 118 is opened as shown in FIG. 6B, the wire 119 is rolled up on the reel 120. The sliding door 118 moves forward in tight contact with the vehicle body when it is closed, and moves backward apart from the vehicle body outwardly when it is opened. In this manner, the sliding door 118 moves at least in two dimensions.
However, there has been an anxiety in the above described structure that the wire 119 may be damaged because the wire 119 has to be rolled up many times on the reel 120. There has been a further problem that application has been difficult, since the wire harness including a number of circuits (electric wires) has poor flexibility.
There has been proposed another structure of installing a wire harness for a sliding door in which a flexible flat cable is arranged from the vehicle body to the sliding door, so that door strokes can be absorbed by bending the flat cable according to opening and closing movement of the sliding door.
However, this structure has had a problem that because the flat cable is composed of printed circuit conductors and insulating sheets having small sectional areas, its power supply capacity is too small and can be only used to supply of electric current having small capacity or signals, but cannot be used for power supply.
There has been a further problem that in case where a small number of electric wires are connected to various functional components by a junction switch system, this would result in an increase of cost.
In order to solve the above described problems, the applicant has proposed in a prior patent application a slack absorbing apparatus for a wire harness in which the wire harness is contained in a sliding door in a state of semi-circular curve, and pushed upward by a leaf spring.
The wire harness is covered with a protective tube such as a corrugated tube made of synthetic resin. The corrugated tube is a tube which is circular in cross section and provided with circumferential grooves and ridges alternately formed in a longitudinal direction.
With opening operation of the sliding door, the sliding door retreats while moving outward away from the vehicle body, and the wire harness inside the sliding door is contracted in diameter. When the sliding door is fully opened, a portion of the wire harness extending from the sliding door to the vehicle body is pulled in a forward direction. On the other hand, with closing operation of the sliding door, the sliding door advances while moving close to the vehicle body, and the wire harness inside the sliding door is enlarged in diameter, and the portion of the wire harness extending from the sliding door to the vehicle body is pulled in a backward direction. In this manner, the slack of the wire harness can be absorbed.
In the above described structure, however, the wire harness has to be arranged diagonally upward from the sliding door to the vehicle body, especially in case where the harness slack absorbing apparatus at the sliding door side or a guide out portion of the wire harness from the harness slack absorbing apparatus is at a lower position than a wire harness at the vehicle body side. Therefore, there has been an anxiety that the wire harness may be caught between the sliding door and the vehicle body.
More particularly, the wire harness is brought near a step (made of a metal panel) of the vehicle body just before the sliding door is closed. On this occasion, the wire harness tends to hang lower than the step, and it has been feared that the wire harness may be caught between the step and a door trim of synthetic resin inside the sliding door. If the wire harness should happen to be caught, the protective tube covering the wire harness may be damaged or the electric wires composing the wire harness may be broken in the worst case. In such a case, power supply to the sliding door and transmission of signals from the sliding door are interrupted, to stop up and down operations of the power windows and opening/closing motions of the sliding door which are electrically driven.
In order to prevent the wire harness from being caught, it has been considered that stronger resiliency may be given to the leaf spring for pushing the wire harness upward. In this case, however, strong pressure is exerted to the wire harness and the protective tube even in a fully open state or a fully closed state of the sliding door in which the leaf spring is not required, and the protective tube is likely to be damaged. In addition, the cost for the leaf spring will be increased.
In case where the wire harness is arranged diagonally upwardly from the sliding door to the vehicle body, it has been feared that the wire harness may be bent at an angle as large as 90 degree, exerting superfluous stress to the bent portion. In this case too, the wire harness may be damaged, or expanding and contracting movement of the wire harness following the opening and closing operation of the sliding door may not be smoothly conducted.
Further, because the corrugated tube has a relatively large diameter and requires a large space for arrangement, there has been problems with respect to space and design that the harness slack absorbing apparatus may become large-sized, and the door trim must be bulged into the vehicle room.
In view of the above described problems, an object of the present invention is to provide a structure of installing a wire harness for a sliding door in which the wire harness will not be caught between the sliding door and the vehicle body with closing operation of the sliding door, superfluous bending force or pressure will not be exerted on the wire harness when the sliding door is opened and closed, or stands still, and which can prevent the wire harness including a protective tube from being damaged or deformed without incurring a cost, and can smoothly and reliably absorb slack of the wire harness at opening and closing of the sliding door, preventing upsizing of the harness slack absorbing apparatus, and improving aesthetic appearance of a door trim.
In order to attain the above described object, there is provided according to the present invention, a structure of installing a wire harness for a sliding door comprising a harness protective tube in which electric wires are contained to compose the wire harness, the harness protective tube being curved at the sliding door side and installed at a vehicle body side, wherein the harness protective tube has an oval shape in cross section, and is curved in a direction of its longer diameter portions at the sliding door side so that the longer diameter portions are positioned in a vertical direction, whereby harness slack absorbing function is imparted to the harness protective tube.
According to a second aspect of the invention, the longer diameter portions of the harness protective tube having an oval shape in cross section are supported by a support part at the sliding door side, and the harness protective tube is curved in a direction of the longer diameter portions extending from the support part to the vehicle body side.
According to a third aspect of the invention, there is further provided a protector in which the support part is positioned, and the harness protective tube having an oval shape in cross section is contained in a curved state in a direction of the longer diameter portions.
According to a fourth aspect of the invention, the longer diameter portions in a curved section of the harness protective tube are urged upward by an elastic member.
According to the invention, by installing the harness protective tube having an oval shape in cross section so as to be curved in a direction of the longer diameter portions, even though the wire harness including the harness protective tube is pulled or hangs down when the sliding door is opened or closed, slack of the wire harness will be rapidly, smoothly and reliably absorbed, because the harness protective tube having an oval shape in cross section exerts strong elastic repulsive force as compared with a harness protective tube having a circular cross section and can be rapidly and reliably restored to the original curved posture. Therefore, the wire harness will not hang down when the sliding door is closed, and a catch of the wire harness between the sliding door and the vehicle body can be avoided. Thus, the wire harness will be prevented from being deformed or damaged.
Moreover, owing to improvement in restoring performance of the wire harness, force of the leaf spring can be made weaker than in the conventional case or the leaf spring can be omitted, resulting in a low cost and simple structure. Further, because the leaf spring will not press the wire harness with strong force, deformation or damage of the wire harness will be prevented.
Still further, because the longer diameter portions of the harness protective tube in an oval shape in cross section are arranged in a vertical direction, and the shorter diameter portions of the harness protective tube are arranged in a direction of thickness of the sliding door, a space in the sliding door for installing the harness can be saved with respect to thickness. Accordingly, a door trim for containing the harness will not bulge or less bulge to improve aesthetic appearance of the door trim, and at the same time, the harness slack absorbing apparatus composed of the harness protective tube can be made compact with respect to thickness.
According to the second aspect of the invention, because the harness protective tube having an oval shape in cross section is curved in a direction of the longer diameter portions in a state where the longer diameter portions are supported by the support part, the wire harness including the harness protective tube will be pulled about the support part as an axis and exert strong restoring force. This will promote the effect of the invention.
According to the third aspect of the invention, because the harness protective tube having an oval shape in cross section is contained in the protector in a state where the longer diameter portions are positioned in a vertical direction, the protector can be made compact in a direction of thickness. Accordingly, the door trim for containing the protector will not bulge or less bulge to improve aesthetic appearance of the door trim. Further, because the wide shorter diameter portions of the harness protective tube having an oval shape in cross section are in contact with a vertical plane of the protector, the posture of the harness protective tube can be stabilized. Accordingly, the longer diameter portions are always positioned in a vertical direction, and the harness protective tube can be always held in a curved state in the direction of the longer diameter portions, thus enhancing harness slack absorbing performance.
According to the fourth aspect of the invention, because the longer diameter portions of the harness protective tube are urged upward by the elastic member, the longer diameter portions are always positioned in a vertical direction, and the harness protective tube can be always held in a curved state in the direction of the longer diameter portions, thus enhancing harness slack absorbing performance. In addition, the restoring force of the harness protective tube is enhanced because the harness protective tube is curved in the direction of the longer diameter portions, the elastic member can be only assisting means. Therefore, the elastic member having a small width can be employed along the longer diameter portion having a small width, and the harness slack absorbing apparatus or the protector can be made compact with respect to thickness.